Have done a search and not really found an answer so for an 02a gearbox can anyone tell me how many pulses come out of the VSS per revolution of the wheels or how many pulses per mile (ppm) thanks
im not sure what this is, the mk2 big block speedo has 1540 printed on the face which refers to some kind of calibration numer (small block speedo is 1505 and the calibration is slightly different) not sure what exactly it refers to but it might be a clue to help you on your way. the 020 and 02a are same in terms of speedo calibration if that helps. what do you need to know for out of interest?
Are those two calibration numbers not the diameter of the wheel in mm for 2 revs of the wheel? 1 Rev of a normal wheel is somewhere in the 750 to 800mm range I think?
all mk2s use the same rolling radius wheel regardless of engine so its not that, tbh it may not be anything to do with ppm or whatever could just be a stock number
and on a 10 inch wide rim for some serious stretch... Rubjonny, I have a gearbox from a mk6 Golf to go on my rado (thought I'd bought a 6 speed 02s till I got it home, but thats another story, bloody ebay sellers) the gearing seems like it will work so I'm going to use it anyway. But it has no speedo drive output so I'm going to fit an ABS ring and use the output from that to drive the speedo, I just need to get the correct ammount of pulses. I've seen many people have stripped the boxes and put the bell housing from an 02a but I dont really want to do that, I want to keep it as is so I can sell again if I dont like it and get the 6 speed 02s
So I had a play with a VSS today, unfortunately the car is in the garage in bits so didn't get any live data so what I have found was done on the bench. Started of by powering the VSS on a 12v supply and monitored the signal pin on a osciloscope, got nothing at all no matter how fast I span it..... School boy error, the VSS signal line gets the voltage from the cluster (5v I beleive) and as the sensor turns it shorts the signal line to ground, giving you a square wave pulse. For one revolution of the VSS you get 4 pulses. Fitted the VSS back to the gearbox and turned the output shafts together, tried this several times to be sure and got a constant 10 pulses per full revolution of the driveshafts With 205/40/17 tyres fitted I will get 859.9 revolutions per mile (figure taken from http://www.rimsntires.com/specs.jsp?item=Wheel-Tire size comparer&sw1=205&ar1=40&bd1=17&rw1=7.5&et1=51&sw2=195&ar2=50&bd2=15&rw2=7.0&et2=45&text1=&text2= ) so I should see 8599 pulses per mile. So my next challenge is to convert the output from an ABS sensor to give me the same. If someone has found any different to this I would be interested to know as I wont know if I got it right till the car is back on the road
